Prior art trailers such as those used in hauling portable equipment, livestock or recreational travel trailers typically use tandem axles. The axles are typically supplied to the trailer manufacturer from the axle manufacturer. The trailer manufacturer must then install and align both axles on the trailer as well as wire or plumb the brakes of each axle assembly to the trailer. Proper alignment of the axles on the trailer can be tedious and time-consuming. Further, once the axle has been installed it is very difficult to realign, and it is often necessary to replace the entire axle if one of the wheel ends has become misaligned or damaged.
Thus an improved axle sub-frame assembly for a trailer is desired which provides for independent alignment and realignment of each wheel, as well as easy installation of the axle sub-frame assembly by the trailer manufacturer.